1. Field of the Invention
The present invention relates to strobe light systems and more particularly to an LED strobe light used by with an imaging device.
2. Description of the Related Art
In the field of image inspection of moving objects a strobe light or stroboscopic lamp, commonly called a strobe, is used to produce regular flashes of light to illuminate the moving object, of which an image is made. A typical commercial strobe light has a flash energy in the region of 10 to 150 joules, and discharge times as short as a few milliseconds, often resulting in a flash power of several kilowatts.
Historically, the light source was often a xenon flash lamp, or flashtube, which has a complex spectrum and a color temperature of approximately 5,600 kelvins. If colored light was desirable, then appropriately colored gels are used to filter the light.
Special calibrated strobe lights, capable of flashing up to hundreds of times per second, are used in industry to stop the appearance of motion of rotating and other repetitively operating machinery and to measure, or adjust, the rotation speeds or cycle times of the equipment. Since this stop is only apparent, a marked point on the rotating body will either appear to move backward or forward, or not move, depending on the frequency of the strobe-flash. If the flash occurs equal to the period of rotation the marked point will appear to not move. Any non-integer flash setting will make the mark appear to move forward or backward, depending on the relative frequency of the strobe light and the rotation of the device.
Linear motion of a test item that is to be inspected requires that an image be formed with a very short shutter speed and/or a very sharply defined light strobe, so that details of the item being inspected can be seen. A problem encountered with prior art LED light strobes is that they have an elongated timeframe in which light is supplied causing the image to be somewhat blurred. Often these LED light strobes use a pulse width modulation to control the duration of the strobed light.
What is needed in the art is an LED strobe system with a sharply defined light pulse.